In-ground swimming pools are typically drained and left empty during the winter months. On some occasions, however, hydrostatic pressure builds up under the pool, especially as a result of spring rains. On such occasions, it is desirable to relieve the hydrostatic pressure by allowing water into the pool. If the hydrostatic pressure is not relieved, and becomes excessive, the in-ground pool will be forced out of the ground altogether and totally destroyed.
Existing relief valves for swimming pools have a plug compressed into a seat by a spring. When hydrostatic pressure under the plug exceeds the pressure of the spring, the plug will be forced out of its seat, and water will enter the pool. The structure for supporting the spring used to push the plug into the seat is typically positioned above the surface of the swimming pool so that the structure can easily be cleaned and will not be clogged with dirt or other debris which would prevent operation of the relief valve. As a result, existing relief valves must be positioned at the deep end of the pool, typically near the drain in the center thereof. If such relief valves were positioned in the shallow end of a pool, the upwardly extending structure supporting the spring would injure the feet of swimmers.
Even though existing relief valves have readily visible spring mechanisms, such valves nonetheless become clogged and fail to operate. Since such valves are typically positioned at the bottom of a pool, they are often under water, and generally unaccessible. As a result, it is difficult to check such relief valves. In many cases, an inoperative relief valve is not detected, and damage is caused to the swimming pool.
Where hydrostatic pressure is strong enough to cause damage to a pool, the water level under the pool is high enough that pressure could also be relieved in the shallow end of the pool. It would be desirable, therefore, to provide a means for relieving hydrostatic pressure which can be installed in the shallow end of the pool and would be substantially flush with the surface of the pool so as not to injure swimmers.